5 Replies Latest reply on May 22, 2013 6:51 AM by Joel Rapoport

    problem with open loop selection for surface lofting

    Joel Rapoport

      hello all,

       

       

      im having a recurring problem for my surface loft feature.

      for this loft im selecting two open loops, with a few guide curves.

      the problem is that whatever changes i make to my part prior to the loft feature, one or both of the open loop profiles gets reversed (or inverted).

      and this is while the changes i have made have nothing to do with this area at all.

      i see no reason for this to happen.

       

      im using the open loop selecting method so i dont have to select each anb every line and curve on that profile. but its getting problematic since i have 7 of these lofts, and each time i make changes to a feature, i have to reconfigure each one of those lofts.

       

      im attaching a few pics to show how the problem looks like:

       

      Untitled-1.jpg

      Untitled-2.jpg

      Untitled-3.jpg

      Untitled-4.jpg

      Untitled-5.jpg

      any idea will be great.

       

      thanks in advance,

      joel

        • Re: problem with open loop selection for surface lofting
          John Burrill

          Hi Joel, instead of using open loop, try using the select group option and then click the tangent-selection hot-spots to pick up the connected edges.  I don't know to a certainty that this will fix your problem with loops flipping direction, but I'd say it's worth a try.  Edges are enumerated in the model topology.  If loops are calculated on the spot, that could explain why their references don't persist.

           

          select_tangent_edges.png

            • Re: problem with open loop selection for surface lofting
              Joel Rapoport

              thanks john,

               

               

              ill try your method tomorow morning and see if it works and i dont get any reversals.

              i usually do it with your selection method, but i have seen that this way is much quicker. but i guess its much problematic too for some reason.

               

              ill let you know how it works out.

               

              is there no way to "lock" a selection of edges? i strange to me that a selection you make gets screwed up...

               

               

              anyway,

              thanks a lot.

              joel

                • Re: problem with open loop selection for surface lofting
                  John Burrill

                  Try creatinga  knit or copy-surface of just the geometry that's providing the edges and then create your loft profiles off of that surface.  Without the extra faces to decide amoung, it might not get confused as easily.

                    • Re: problem with open loop selection for surface lofting
                      Joel Rapoport

                      thanks john,

                       

                       

                      i took your advice, and used a copy surface for my profiles. but surface loft gave me problems so i used boundry instead and i think its working a lot better.

                      i still get some rebuild errors when i change features before the boundrys, but not all of the boundry features at least.

                      its a nice work around.

                       

                      Untitled-1.jpg

                       

                      my big problem with this issue is that i am giving the original solid files to my client and i dont want him to have errors and not know why they happen, or think that my design is not as good as can be. but i guess thats the best i can do for now on this part.

                       

                       

                       

                      thanks again,

                      joel

                    • Re: problem with open loop selection for surface lofting
                      Robert Stupplebeen

                      Joel,

                      My understanding of the situation is that behind the scenes each face has a number and each edge of the face has a number. When you change items upstream the numbering system is resolved causing the issues. SolidWorks attempts to sort this out behind the scenes but in the end it only gets fairly useless errors from the parasolid kernel. When I have hit these situations I tend to recreate some or all of the geometry in slightly different ways until I have a robust solution. I am sorry I can't provide more optimistic feedback but hopefully knowing others feel your pain and the knowledge that it isn't 'gremlins' will help.

                      Rob Stupplebeen